Karl Marx, the philosopher, economist, political theorist and socialist revolutionary, is best-known for the 1848 pamphlet, The Communist Manifesto and the three-volume Das Kapital. His theories, called Marxism, maintained that class conflict leads to the development of human societies and that internal tension were inherent in capitalism, which would ultimately be replaced by the socialist mode of production.
Erich Fromm was a German social psychologist, psychoanalyst, sociologist, and socialist. A German Jew, he fled the Nazi regime and settled in the United States. He was a co-founder of The William Alanson White Institute and was associated with the Frankfurt School of critical theory. He is best remembered for authoring the book Escape from Freedom.
Max Weber was a German historian, political economist, jurist, and sociologist. Widely regarded as one of the most influential and important theorists, Weber's ideas had a profound influence on social research and social theory. Although he did not see himself as a sociologist, Weber is often counted among the fathers of sociology alongside Émile Durkheim, Auguste Comte, and Karl Marx.
One of the most prominent intellectuals of the 20th century, Theodor Adorno was a pioneer of the Frankfurt School of Critical Theory and despised the culture industry. Born to a singer mother, the German sociologist grew up amid music and could even play Beethoven on the piano by 12.
The proponent of the Frankfurt School of critical theory, Herbert Marcuse largely influenced the leftist student revolts of the 1960s. Equipped with a PhD in German literature, he wrote Hegel’s Ontology and the Theory of Historicity, with Martin Heidegger. His Eros and Civilization spoke at length about capitalism.